Short answer
None of the four. The New Testament did not exist while Jesus was alive. He preached around the year 30. Mark, the earliest New Testament Gospel, was written some thirty-five years later, and John near the end of the century. The first surviving list of exactly these twenty-seven books comes from the year 367. When Jesus said "it is written", he quoted the Law and the Prophets, the scriptures already written in his day. Yet Mark says Jesus came preaching "the gospel" and told people to believe it. So the Injil (the Gospel Jesus preached) existed before there were any New Testament Gospels. It was a message from God (﷾) in Jesus' mouth, not a book about him. That is what the Qur'an means when it says God (﷾) gave Jesus the Injil.
Full explanation
Jesus came first, the books came later
Jesus preached in Palestine around the year 30. The earliest New Testament writings are letters by Paul, a Christian missionary of the first century, from about 50. Scholars date Mark to about 65-70, Matthew and Luke to the 80s, and John to the end of the century.
A standard textbook. It dates Paul's earliest letters to around 50 CE, Mark to about 65-70, Matthew and Luke to about 80-85, and John to about 90-95, and notes that Jesus spoke Aramaic while the Gospels were written in Greek by authors who do not name themselves. It also says Paul did not know Jesus during Jesus' lifetime and came to faith only after the crucifixion.
The collection was settled three centuries later
For three centuries the churches disagreed about which books belonged. Some read the Shepherd of Hermas, an early Christian book, as scripture. Some rejected Hebrews, Revelation or James. The Syrian churches used a different set. The first surviving list of exactly today's twenty-seven books is a letter by Athanasius, a bishop of Alexandria, in 367.
Athanasius, bishop of Alexandria, lists the books he counts as scripture. His New Testament list is the twenty-seven books of today's New Testament, the earliest surviving list of exactly these books and no others.
Traces how the churches came to agree on the New Testament. For three centuries books such as Hebrews, James and Revelation were disputed, and some read the Shepherd of Hermas as scripture. Athanasius' letter of 367 is the first surviving list of exactly the twenty-seven books; councils at Hippo (393) and Carthage (397) confirmed it; the Syrian churches long used a shorter set.
Jesus preached "the gospel" before any New Testament Gospel existed
Mark, the earliest New Testament Gospel, says Jesus came into Galilee preaching "the gospel" and telling people to believe it. Matthew and Luke say the same. In every case "the gospel" (the word means good news) is a message he spoke, not a book.
“Now after that John was put in prison, Jesus came into Galilee, preaching the gospel of the kingdom of God, And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.”
“And Jesus went about all Galilee, teaching in their synagogues, and preaching the gospel of the kingdom, and healing all manner of sickness and all manner of disease among the people.”
“The Spirit of the Lord is upon me, because he hath anointed me to preach the gospel to the poor; he hath sent me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty them that are bruised,”
His scripture was the Law and the Prophets
When Jesus said "it is written", he was quoting the Hebrew scriptures: the Law, the Prophets and the Psalms. In his lifetime no New Testament book had been written. Even the famous line that all scripture is inspired comes straight after the scriptures that Paul's young helper Timothy had known from childhood. No New Testament existed then.
“But he answered and said, It is written, Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God.”
“And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.”
“And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:”
Paul preached "my gospel"
About a quarter of a century after Jesus, Paul called the message he preached "my gospel". He also warned the Galatians, Christians in what is now Turkey, against "another gospel" taught by rival preachers. The word still meant a preached message.
“In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.”
“I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel: Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.”
What the Qur'an means by the Injil
The Qur'an says God (﷾) sent Jesus the Injil, with guidance and light. The Injil confirmed the Torah (the book God (﷾) gave Moses) that came before it. The Qur'an says God (﷾) taught Jesus the Law and the Injil. It records Jesus saying that God (﷾) had given him revelation. The Injil is what God (﷾) gave to Jesus, not what others later wrote about him.
“And in their footsteps We sent Jesus the son of Mary, confirming the Law that had come before him: We sent him the Gospel: therein was guidance and light, and confirmation of the Law that had come before him: a guidance and an admonition to those who fear Allah.”
“Then, in their wake, We followed them up with (others of) Our messengers: We sent after them Jesus the son of Mary, and bestowed on him the Gospel; and We ordained in the hearts of those who followed him Compassion and Mercy. But the Monasticism which they invented for themselves, We did not prescribe for them: (We commanded) only the seeking for the Good Pleasure of Allah; but that they did not foster as they should have done. Yet We bestowed, on those among them who believed, their (due) reward, but many of them are rebellious transgressors.”
“"And Allah will teach him the Book and Wisdom, the Law and the Gospel,”
“He said: "I am indeed a servant of Allah: He hath given me revelation and made me a prophet;”
Where the Injil survives
Luke opens by saying that others had handed the story down to him. He says he wrote an ordered account from what they delivered. What remains of the Injil survives inside four such accounts. They keep parts of Jesus' message, but they are reports about Jesus, not the Injil God (﷾) gave him. That fits what the Qur'an says.
“Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word; It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,”
A standard textbook. It dates Paul's earliest letters to around 50 CE, Mark to about 65-70, Matthew and Luke to about 80-85, and John to about 90-95, and notes that Jesus spoke Aramaic while the Gospels were written in Greek by authors who do not name themselves. It also says Paul did not know Jesus during Jesus' lifetime and came to faith only after the crucifixion.
Verse by verse
1 Corinthians 15:3-4 — First Epistle to the Corinthians, chapter 15, verses 3-4
“For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures:”
Cited for
Christians say the gospel is the news that Christ died for our sins and rose again.
The response
That is how Christians preached "the gospel" after Jesus had gone. But Mark says Jesus preached "the gospel" in Galilee at the very start of his work, long before any talk of a cross. He told people to repent and believe it then.
Where it lands — The Injil Jesus preached at the start of his mission cannot have been the news Christians tell of his death.
Luke 1:1-3 — Gospel of Luke, chapter 1, verses 1-3
“Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word; It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,”
Cited for
Christians hold that the four New Testament Gospels faithfully record what Jesus preached.
The response
Luke says many had already written accounts, and that it "seemed good to me also" to write one from what eyewitnesses handed down. That is a careful report about Jesus. It is not the Injil that God (﷾) gave to Jesus.
Where it lands — By their own words, the New Testament Gospels are accounts about Jesus, not the revelation he was given.
Perspectives
Mainstream Christian
Christians hold that the gospel is the good news that Christ died for our sins and rose again. They say the disciples preached it, and that the four New Testament Gospels record it faithfully from eyewitness testimony.
Paul defines the gospel as a message. It is that Christ died for our sins, was buried and rose on the third day.
Rebuttal
Paul gave this summary in his letters, after Jesus had gone. Mark has Jesus himself preaching "the gospel" in Galilee at the start of his work and telling people to repent and believe it. So the Injil Jesus preached was not Paul's summary.
Luke drew on those who were eyewitnesses from the beginning, so the New Testament Gospels preserve what Jesus taught.
Rebuttal
Luke does say he used what eyewitnesses handed down, and the New Testament Gospels keep parts of Jesus' message. But Luke says it "seemed good to me also" to write an ordered account, after many others had written. That is a report about Jesus, not the Injil God (﷾) gave him.
The Islamic perspective
The Injil was the revelation God (﷾) gave Jesus, which he preached aloud to the people of Israel. The four New Testament Gospels are later accounts about him. They keep parts of his message, but they are not the book he was given.
The New Testament did not exist in Jesus' lifetime. Its earliest books date from about 50 CE, and the first surviving list of all twenty-seven is from 367 CE.
Mark records Jesus preaching "the gospel" and calling people to believe it, decades before any New Testament Gospel was written.
When Jesus appealed to scripture, he quoted the Law, the Prophets and the Psalms.
The Qur'an teaches that God (﷾) gave Jesus the Injil as guidance and light.
Luke presents his Gospel as an ordered account compiled from others, not as revelation given to him.